1. Field of the Invention
The present invention relates to offshore platforms anchored to a seafloor with tendons and having a lateral mooring system (LMS) for use the oil and gas industry, where the LMS affords improved horizontal stability, improved platform positioning, improved platform installation, and improved platform operations and to methods for installing and using same.
More particularly, the present invention relates to TLPs or other similar offshore platforms having a lateral mooring system (LMS) for use in the oil and gas industry and in particular, to TLPs and extend-base tension leg platforms (ETLPs), where the LMS is adapted to reduce installation and/or operation costs and to provide multiple installation and/or operation performance benefits such as improved horizontal stability, improved platform installation, improved platform operations and to methods for platform positioning, installation, and operation using the LMS.
2. Description of the Related Art
Many offshore platform and platform substructures have been described in the prior art. Many of these substructures are so-called large platform support structures that anchor to the seabed by means of an array of tendons. These tendons form a pattern that define the boundaries of a relatively large area of the seabed. Compact substructures are also known in the art, but they generally employ a central column with radially disposed arms. Such large and compact platforms are disclosed in the following U.S. Pat. Nos: 3,982,492, 4,421,436, 4,793,738, 4,913,233, 4,938,632, 4,983,073, 5,147,148, 5,381,865, 5,421,676, 5,431,511, 5,433,273, 5,549,164, 5,507,598, 5,567,086, 5,669,735, and 5,775,846, incorporated herein by reference. However, these structures do not include features of the present invention. For example, these structures do not include an array of arms or wings that radiate outwardly from a multi-columned, wave transparent substructure that minimizes or at least reduces the fatigue imposed on the anchoring tendons.
More recently, tension leg platforms including lateral extension to extend the platforms base have been developed and are the subject of U.S. Pat. No. 6,447,208, incorporated herein by reference, incorporated herein by reference.
Although TLPs, ETLPs and other offshore platforms used in the oil and gas industry are used in many offshore drilling and production applications, there is still a need in the art for improving installation and/or operation of the such platforms, especially during initial positioning, installation, and post-installation operations.